We have some unexpected behaviour with POCO::JSON implementation. There are two main problems that touches Json encoding and decoding:1) Encoding and decoding of buffer that contains zero byte(s) sequence. It is impossible to decode sequence that was previously encoded with POCO Json.2) Encoding of the bytes/characters that need to be encoded to have compatibility with many well-known Json libraries. Zero byte, Upper ASCII and utf-8 multi-byte characters expected to be encoded.We have implemented some serialization messages classes based on POCO Json implementation, but have several inequality of implementations of POCO and client-side libraries.

JSON library is in early stages. There have been some breaking changes recently, most significantly internalized and reference counted DefaultHandler (renamed to ParseHandler) for 1.5.2 releas; there will be more significant changes in the future (most notably, as things currently stand, we plan o substitute the parser with a much faster one from sandbox Poco::Web).

With all that said, please submit a GitHub issue with detailed description of what you expect to see in regards to enconding/decoding. A pull-request would be even better and give you much faster turnaround to release.